1. Field of the Invention
The present invention relates generally to eyeglasses. More particularly the invention relates to an eyeglass device for improving the far field of vision for myopia sufferers, while maintaining the user horizontal line-of-sight and lower field of vision substantially unobstructed.
2. Prior Art
Myopia, more commonly known as nearsightedness, is a condition of the eye which causes distant object to be out of focus, while an object closer to the viewer is in focus. This occurs when light entering the eye through the cornea and lens does not directly focus on the retina but instead converges in front of it. Conventionally, myopia can be corrected through the use of corrective lenses in eyeglasses or contacts. In general, the corrective lens will have a diverging lens, which is a lens with negative optical power (i.e. concave). This compensates for the deficiency by essentially moving the focal length back towards the retina thereby correcting vision.
Many corrective lens types are known in the art. Single vision correction type lenses are the most common lens type and conventionally have a uniform optical correction over the entire area of the lens. Conventionally, single vision lenses are shaped to cover the entire optic or field of vision of the wearer in order to correct deficiencies affecting the entire field. However, half field lenses, which are smaller and sit lower on the nose, are also known and typically employed to correct near field vision deficiencies, which inhibit the ability to see small characters and lines and to read. Such reading glasses generally are a magnifying lens which brings close typeface and small objects into focus for users who are far sighted or just suffer from a lack of close-focus.
Magnifying lenses may cover the entire eye, but most users prefer that their long vision be unobstructed when reading or doing close work with magnifying lenses in their eyeglasses. As such a large majority of magnifying lens eyeglasses which are employed by users for reading and close up work, are half height lenses which are worn on the nose in a manner where the user looking downward as would be the case with reading, can focus on the type on the page being read, through the half lenses in a downward gaze.
In this conventional fashion, with the user viewing substantially downward in their lower field of vision (for example when reading), by using half height lenses in eyeglass frames, the configuration essentially splits the users field of vision in two, with the lower field being corrected by the magnification lenses in the eyeglasses, and the upper field, which is not in line with the lenses, are un-corrected.
Bifocal is another type wherein the field of vision is additionally split into upper and lower sections, however both having corrective lens portions. The upper section of the lens is generally used for far field vision when looking slightly upward, while a lower section is used for near field vision. A user with vision deficiencies in both the upper and lower fields of vision would employ a certain lens power in the upper section for far field vision, while having a different power lens in the lower section for near field vision correction if needed.
However, for some myopia-affected users, or users requiring other correction, conventional single vision and bifocal lenses do not suitably correct their vision, especially in cases where only their far field (upper field) vision is affected, and their near field (lower field) vision is relatively normal and may not need any substantial correction. For instance, single vision lenses which cover the entire field of the wearers vision would cause over-correction and vision problems for the otherwise unaffected near field of vision, while bifocal lenses would simply be unusable since correction of the near field (lower section) is not needed in the first place.
A particular prominent occurrence of this problem is seen in the medical field. Surgeons and other medical professionals are typically required to maintain excellent vision for obvious reasons. In cases where a surgeon has far field vision deficiencies, the need for corrective eyewear to give the professionals the best vision possible is more then obvious. However, in cases where the individual has excellent near field vision, there is an additional obvious need to leave the straight ahead horizontal line of sight and near field of vision unobstructed by the corrective eyewear.
A particular problem exists for surgeons. The surgeon, when performing medical surgical procedures, will typically shift viewing fields from a field view looking downward at a surgical table, to a horizontal line-of-sight viewing when communicating with others who are close by. Further, in modern operating rooms, with overhead visual displays employed for surgery, looking up at the closer-positioned display screens with writing on them as well as a graphic display, diagnostic machinery, can require close-up correction of magnifying lenses using what would be an overhead gaze of the eyes while the surgeon's face is still angled downward toward the surgical site. In the alternative, the straight-ahead viewing may require another type of corrective lens, however the user still requires an unobstructed downward view or gaze at the same time.
As can be ascertained, the need for eyewear providing unobstructed downward viewing for arms length work and the user's eye gaze at a downward angle from the plane of the face, while maintaining corrected vision looking straight ahead, gazing the eyes upward with a downward angled face, is a need unanswered by conventional eyewear.
Prior art has taught some examples of devices which are aimed to solve this problem. U.S. Pat. No. 6,174,059 to Haley teaches eyeglasses configured to provide the wearer a substantial upper vertical corrected field of vision and a substantial lower vertical uncorrected field of vision. The eyeglasses enable the user to see objects at a distance through the lenses and objects that are relatively near through the lower vertical uncorrected field of vision, such as reading relatively fine print. However, these and similar devices fail in providing adequate unobstructed vision when viewing close objects being substantially straight ahead in their horizontal line-of-sight and in the lower field of vision. This can be attributed to the shape and construction of the lenses, which do not facility unobstructed horizontal line-of-sight as well as lower field of vision deemed suitable for medical professionals.
As a result, there is a continuing unmet need for an eyewear device employing corrective lenses which are configured to provide corrected vision on an upward or forward gaze of the eyes, leaving the horizontal and downward gaze or line of sight substantially unobstructed by the corrective lens. Such a device should do so when the user has a face tilted downward but may change their eye gaze from that same downward angle to one upward. Such a device should be especially suitable for myopia affected persons or provide the correction for their forward and upward gaze while leaving the line of sight with a lowered angle of the eyes, unobstructed. Such a device should advantageously provide a means for adjusting the viewing angle of the eyewear lenses as needed for customizing the viewing characteristics in the upper field of vision as deemed suitable by the wearer, such as to match the plane of a video screen. Further, such a device should be configured for easy employment by medical professionals and other individuals where vision quality is of an upmost importance.
The forgoing examples of related art and limitation related therewith are intended to be illustrative and not exclusive, and they do not imply any limitations on the invention described and claimed herein. Various limitations of the related art will become apparent to those skilled in the art upon a reading and understanding of the specification below and the accompanying drawings.